ПОСТРОЕНИЕ РЕШЕНИЙ КУСОЧНО-ЛИНЕЙНЫХ ФАЗОВЫХ СИСТЕМ

The creation of methods for the study of nonlinear phase systems has a long history, since the 60s of the last century (V.I. Tikhonov, V. Lindsay, M.V. Kapranov, B.I. Shakhtarin, etc.). By now, rigorous and approximate analysis methods of such systems have been developed. However, most methods are limited to the analysis of low order systems. Only in recent years attempts have been made to create methods, which allow to carry out the analysis of high-order phase systems. The material of this article deals with these methods. The article considers the construction of solutions of phase systems on the example of phase-locked frequency of arbitrary dimension with piecewise linear approximation of the nonlinear function. This approximation allowed to use an explicit form of solutions in the linearity and to obtain analytical conditions for the existence of various types of system behavior. The analytical conditions for the existence of solutions leading to the emergence of complex limit sets of the trajectories of phase systems and their bifurcations are obtained. These are homoclinic trajectories in the case of the saddle-focus equilibrium state, which play a decisive role in the occurrence of chaos. It is also shown that it is possible to obtain analytical conditions for the bifurcation of the birth and the existence of multi-pass rotational cycles in a piecewise linear phase system, on the basis of which a criterion for the transition to chaos through bifurcations cascade of doubling the stable cycle period can be obtained; in accordance with the Sharkovsky theorem it ends with the bifurcation of the cycle birth of the period three and the occurrence of developed chaos. It should be noted that the research methods of piecewise linear systems described in the paper were applied by the authors not only to phase systems, but, for example, to the Chua system, allowing various chaotic behavior.Создание методов исследования нелинейных фазовых систем имеет длительную историю, начиная с 60-х годов прошлого века (В.И. Тихонов, В. Линдсей, М.В. Капранов, Б.И. Шахтарин и др.). К настоящему времени разработаны строгие и приближенные методы анализа таких систем. Однако большинство методов ограничиваются анализом систем невысокого порядка. Лишь в последние годы предприняты попытки создания методов, позволяющих проводить анализ фазовых систем высокого порядка. К таким методам относится и материал данной статьи. В статье рассмотрено построение решений фазовых систем на примере фазовой автоподстройки частоты произвольной размерности с кусочно-линейной аппроксимацией нелинейной функции. Такая аппроксимация позволила использовать явный вид решений в областях линейности и получить аналитические условия существования разнообразных типов поведения этой системы. Получены аналитические условия существования решений, приводящих к возникновению сложных предельных множеств траекторий фазовых систем и их бифуркаций. Это гомоклинические траектории в случае состояния равновесия типа седло-фокус, играющие решающую роль в возникновении хаоса. Также показана возможность получения аналитических условий бифуркации рождения и существования многообходных вращательных циклов в кусочно-линейной фазовой системе, на основе которых может быть получен критерий перехода к хаосу через каскад бифуркаций удвоения периода устойчивого цикла, который в соответствии с теоремой Шарковского заканчивается бифуркацией рождения цикла периода три и возникновением развитого хаоса. Следует отметить, что описанные в работе методы исследования кусочно-линейных систем применялись авторами не только к фазовым системам, но, например, к системе Чуа, допускающей разнообразное хаотическое поведение

ПРОЕКТНОЕ ОБУЧЕНИЕ В ПРОГРАММАХ БАКАЛАВРОВ РОБОТОТЕХНИЧЕСКОГО ПРОФИЛЯ

In the article the author imparts the experience of teaching project disciplines using medium-level computer systems beginning with lower level with the further transition to upper level systems. The results of the introduction of an experimental technique of teaching project training are given. The article considers the introduction of an experimental technique of project training in the course "The fundamentals of robotic systems automation". The project suggests applying CAD systems to develop a geometrical model of a submersible craft, which will be used in future to design project documentation as well as a control system and a simulator. The project distinction is affected with conditions of individual assignment fulfilment without using ready solutions. The project subject-matter is defined with knowledge system of future bachelor specialization in the area of robotics. The article demonstrates stage methods of training and supervision over project fulfilment with IT application according to modular approach. In practice bachelors take intense interest in theoretical and practical project-based learning if they use modern IT.В статье авторы делятся опытом преподавания проектных дисциплин с применением компьютерных систем среднего уровня, начиная с младших курсов с последующим переходом к системам верхнего уровня. Приводятся результаты внедрения экспериментальной методики преподавания проектного обучения. Предлагается внедрение экспериментальной методики проектного обучения в курсе «Основы автоматизированного проектирования робототехнических систем». В проекте предполагается использование CAD-систем для разработки геометрической модели подводного аппарата, которая в дальнейшем используется для создания проектной документации, а также для отработки системы управления и симулятора. Индивидуальность проекта усложняется условиями самостоятельного выполнения задания без возможности заимствований и использования готовых решений. Тематика проекта определяется комплексом знаний будущей специализаций бакалавра в области робототехники. Показаны поэтапные способы обучения и контроля выполнения проекта с применением информационных технологий по модульному принципу. На практике отмечен повышенный интерес бакалавров к теоретическим и практическим вопросам проектирования, если они используют современные IT-технологии

Имитационные комплексы для подготовки операторов подводных аппаратов

In the article issues of the organization of imitating modeling complexes for training operators of Remotely Operated Underwater Vehicle are considered. It is reported about practical development of sea exercise simulation in Bauman MSTU.В статье рассматриваются вопросы организации имитационных моделирующих комплексов для подготовки операторов телеуправляемых подводных аппаратов. Сообщается о практических разработках морских тренажеров в МГТУ им. Н.Э. Баумана

Алгоритм оценки параметров широкополосного сигнала на ограниченном интервале наблюдения

This article deals with the algoritm of frequency estimation of a spread spectrum signals based on the parametric method of spectrum analysis which allows to improve accuracy of frequency estimation by multiple repetition of the calculation procedure of the autocorrelation function within a limited data length of the signal and with the use of a parametric method of spectrum analysis.Предлагается алгоритм оценки частоты широкополосного сигнала на основе параметрического метода спектрального анализа, который позволяет повысить точность оценки частоты за счет многократного повторения процедуры вычисления автокорреляционной функции в пределах ограниченной выборки сигнала и с использованием параметрического метода спектрального анализа

Thyroid cancer risk in Belarus among children and adolescents exposed to radioiodine after the Chornobyl accident

BACKGROUND: Previous studies showed an increased risk of thyroid cancer among children and adolescents exposed to radioactive iodines released after the Chornobyl (Chernobyl) accident, but the effects of screening, iodine deficiency, age at exposure and other factors on the dose-response are poorly understood. METHODS: We screened 11 970 individuals in Belarus aged 18 years or younger at the time of the accident who had estimated (131)I thyroid doses based on individual thyroid activity measurements and dosimetric data from questionnaires. The excess odds ratio per gray (EOR/Gy) was modelled using linear and linear-exponential functions. RESULTS: For thyroid doses \u3c5 \u3eGy, the dose-response was linear (n=85; EOR/Gy=2.15, 95% confidence interval: 0.81-5.47), but at higher doses the excess risk fell. The EOR/Gy was significantly increased among those with prior or screening-detected diffuse goiter, and larger for men than women, and for persons exposed before age 5 than those exposed between 5 and 18 years, although not statistically significant. A somewhat higher EOR/Gy was estimated for validated pre-screening cases. CONCLUSION: 10-15 years after the Chornobyl accident, thyroid cancer risk was significantly increased among individuals exposed to fallout as children or adolescents, but the risk appeared to be lower than in other Chornobyl studies and studies of childhood external irradiation

BMI, Diet and Female Reproductive Factors as Risks for Thyroid Cancer: A Systematic Review

Background: Thyroid cancer incidence rates have been increasing worldwide but the reason behind this is unclear. Both the increasing use of diagnostic technologies allowing the detection of thyroid cancer and a true increase in thyroid cancer incidence have been proposed. This review assesses the role of body mass index (BMI), diet, and reproductive factors on the thyroid cancer trend. Methods: Epidemiologic studies of the selected risk factors up to June 2010 were reviewed and critically assessed. Results: Among the thirty-seven studies reviewed and despite variation in the risk estimates, most papers supported a small but positive association for BMI (risk estimate range: 1.1–2.3 in males and 1.0–7.4 in females.). Among specific dietary components, there was no consistent association of thyroid cancer risk with iodine intake through fortification (risk estimate range: 0.49–1.6) or fish consumption (risk estimate range 0.6–2.2), nor with diets high in cruciferous vegetables (risk estimate range 0.6–1.9). A small number of studies showed a consistent protective effect of diets high in non-cruciferous vegetable (risk estimate range: 0.71–0.92). Among reproductive factors (pregnancy, parity, number of live births, use of prescription hormones, menstrual cycle regularity, and menopausal status), none were consistently associated with higher thyroid cancer risk. Conclusions: BMI had the strongest link to thyroid cancer risk among those examined. Detailed examinations of populationleve

STRESS-STAIN STATE MONITORING SYSTEM OF COMPOSITE STRUCTURES WITH THE MECHANOLUMINESCENT SENSORS

At present, the intensive use of composite materials for the creation of various parts of aviation equipment is noted. The irreplaceability of composites is provided by a combination of such important characteristics as high mechanical strength, heat resistance, corrosion resistance, low density. Due to its complex structure, composite panels can have the intellectual property of self-diagnostics of their condition. Structurally, the composite panel is a matrix reinforced with fibers. Optical sensors embedded into composite matrix transmit radiation trough the reinforcing glass fiber. So, an autonomous information-measuring system can be created. To control the stress-strain state of composite structures, it is proposed to incorporate mechanoluminescent sensors into the structure of composites. The phosphors of the AIIBVI group possess the ability to generate radiation under mechanical loading (mechanoluminescence). Such sensors are light-generating, non-volatile, solid-state, miniaturized. When the composite structure is deformed, the sensors generate mechanoluminescent radiation transmitted along the reinforcing fibers to the photodetector device and to the signal processing unit, in which the localization and magnitude of the mechanical action on the composite panel are analyzed. The physical principles of mechanoluminescent sensor elements are described in the article, a mathematical model of transformation is presented, which allows calculating the output light flux of the sensor under mechanical actions of different duration and magnitude. On the basis of the mathematical model, an application is realized in the MATLAB for modeling the optical signal of sensors with different parameters when the amplitude-time parameters of the input effect change. According to the mathematical model, an algorithm for processing the signal of a mechanoluminescent sensor has been developed, which makes it possible to perform an inverse transformation – to restore the parameters of the input mechanical action by the light flux

THE CONSTRUCTION OF SOLUTIONS OF PIECEWISE-LINEAR PHASE SYSTEMS

The creation of methods for the study of nonlinear phase systems has a long history, since the 60s of the last century (V.I. Tikhonov, V. Lindsay, M.V. Kapranov, B.I. Shakhtarin, etc.). By now, rigorous and approximate analysis methods of such systems have been developed. However, most methods are limited to the analysis of low order systems. Only in recent years attempts have been made to create methods, which allow to carry out the analysis of high-order phase systems. The material of this article deals with these methods. The article considers the construction of solutions of phase systems on the example of phase-locked frequency of arbitrary dimension with piecewise linear approximation of the nonlinear function. This approximation allowed to use an explicit form of solutions in the linearity and to obtain analytical conditions for the existence of various types of system behavior. The analytical conditions for the existence of solutions leading to the emergence of complex limit sets of the trajectories of phase systems and their bifurcations are obtained. These are homoclinic trajectories in the case of the saddle-focus equilibrium state, which play a decisive role in the occurrence of chaos. It is also shown that it is possible to obtain analytical conditions for the bifurcation of the birth and the existence of multi-pass rotational cycles in a piecewise linear phase system, on the basis of which a criterion for the transition to chaos through bifurcations cascade of doubling the stable cycle period can be obtained; in accordance with the Sharkovsky theorem it ends with the bifurcation of the cycle birth of the period three and the occurrence of developed chaos. It should be noted that the research methods of piecewise linear systems described in the paper were applied by the authors not only to phase systems, but, for example, to the Chua system, allowing various chaotic behavior